An outbreak of salmonellosis among horses at a veterinary teaching hospital

Between May 1996 and February 1997, 27 horses and a veterinary student at a veterinary teaching hospital developed apparent nosocomial Salmonella Typhimurium infection. The source of the multiple-drug resistant Salmonella Typhimurium was a neonatal foal admitted for treatment of septicemia. A high infection rate (approx 13% of hospitalized horses) coupled with a high case fatality rate (44%) for the initial 18 horses affected led to a decision to close the hospital for extensive cleaning and disinfection. Despite this effort and modification of hospital policies for infection control, 9 additional horses developed nosocomial Salmonella Typhimurium infection during the 6 months after the hospital reopened. Polymerase chain reaction testing of environmental samples was useful in identifying a potential reservoir of the organism in drains in the isolation facility. Coupled with clinical data, comparison of antimicrobial resistance patterns of Salmonella Typhimurium isolates provided a rapid initial means to support or refute nosocomial infection. Although minor changes in the genome of these isolates developed over the course of the outbreak, pulsed-field gel electrophoresis testing further supported that salmonellosis was nosocomial in all 27 horses.     

Serologic survey for Borrelia burgdorferi antibody in horses referred to a mid-Atlantic veterinary teaching hospital

Blood samples obtained from 13 of 100 (13%) and 6 of 91 (7%) horses at the George D. Widener Hospital for Large Animals in the months of June and October, respectively, had antibody to Borrelia burgdorferi as determined by ELISA. Horses from the states of New York, Maryland, Delaware, New Jersey, and Pennsylvania were seropositive for B burgdorferi. The frequency of antibody response in horses from New Jersey was greater (P less than 0.05) than the frequency of antibody response in horses from Pennsylvania or that of horses from the other states combined. Statistically significant difference was not found when a comparison was made between horses with serotiter and open diagnosis of neurologic or musculoskeletal disease and horses with negative serotest results and open diagnosis of neurologic or musculoskeletal disease.     

Risk factors for methicillin-resistant Staphylococcus aureus colonization in horses admitted to a veterinary teaching hospital

Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging problem in horses; however, the epidemiology of infection and colonization is poorly understood. This study evaluated factors associated with MRSA colonization at the time of admission to a veterinary teaching hospital. A case-control study evaluating historical factors was performed. Previous colonization of the horse, previous identification of colonized horses on the farm, antimicrobial administration within 30 days, admission to the neonatal intensive care unit, and admission to a service other than the surgical service were risk factors for community-associated colonization. A better understanding of risk factors for MRSA colonization is important to elucidate the epidemiology of this emerging veterinary and zoonotic pathogen, and to design evidence-based infection control programs.     

In vitro evaluation of various quinolone antibacterial agents against veterinary mycoplasmas and porcine respiratory bacterial pathogens

The in vitro activities of 12 quinolones and four antibiotics were determined against 15 veterinary mycoplasmal species and four species of bacteria commonly involved in respiratory infections in pigs. The newer quinolones were markedly more active in vitro against a wide range of mycoplasmas than nalidixic acid and the earlier quinolones. Against Mycoplasma hyopneumoniae ciprofloxacin was the most active quinolone with a geometric mean minimal inhibitory concentration (MIC) against 16 strains of 0.01 microgram ml-1 compared with 0.04 microgram ml-1 for tiamulin, 0.06 microgram ml-1 for tylosin, 0.17 microgram ml-1 for oxytetracycline and 0.23 microgram ml-1 for gentamicin. M hyosynoviae was less sensitive to the quinolones with mean MICs of 0.6 microgram ml-1 for ofloxacin and 0.7 microgram ml-1 for ciprofloxacin compared with 0.034 microgram ml-1, or less, for tiamulin. Norfloxacin and its 6-chloro analogue were both mycoplasmacidal in vitro at five or 10 times their MICs against M hyopneumoniae UCD4. Tiamulin was mycoplasmastatic. The quinolones were also active against porcine Bordetella bronchiseptica and Pasteurella multocida strains and Haemophilus species. Ciprofloxacin was the most active quinolone with mean MICs of 0.58 microgram ml-1 against B bronchiseptica (nine strains), 0.026 microgram ml-1 against P multocida (five strains) and 0.01 microgram ml-1, or less, against Haemophilus pleuropneumoniae (nine strains) and H parasuis (two strains) compared with mean MICs of from 0.5 microgram ml-1 to 64 micrograms ml-1, or more, for the antibiotics. This combination of excellent mycoplasmacidal activity against M hyopneumoniae and good antibacterial activity, suggests that the quinolones have great potential for treating respiratory infections in pigs, including enzootic pneumonia.     

Evaluation of a PCR to detect Salmonella in fecal samples of horses admitted to a veterinary teaching hospital.

The diagnostic accuracy of a PCR used to identify horses shedding Salmonella spp. in their feces during hospitalization was estimated, relative to bacterial culture of serially collected fecal samples, using longitudinal data. Five or more fecal samples were collected from each of 116 horses admitted as inpatients, for reasons other than gastrointestinal disease, between July 26, 2001 and October 25, 2002. All 873 fecal samples collected were tested with a PCR based on oligonucleotide primers defining a highly conserved segment of the histidine transport operon gene of Salmonella typhimurium, and each sample was cultured for Salmonella spp. One or more samples from 87 (75%) horses were PCR positive, and Salmonella was cultured from 1 or more samples from 11 (9.5%) horses. All culture-positive horses had at least 1 PCR-positive result, whereas only 29 (28%) culture-negative horses were PCR negative on all fecal samples tested. The PCR was most specific, relative to bacterial culture of serially collected fecal samples, when used to test samples from Quarterhorse or breeds other than Thoroughbred or Standardbred, or from clinical (vs. healthy, accompanying horses) cases. Overall, the PCR had the greatest agreement (70%), compared with bacterial culture of serially collected fecal samples, using a cutoff of 2 or more positive PCR test results to define a Salmonella-positive horse. The reasons why some fecal samples, from which Salmonella organisms cannot be isolated, are PCR positive need to be determined before the PCR can be incorporated into Salmonella surveillance programs for hospitalized equine populations.     

Aspects of bacterial resistance to antimicrobials used in veterinary dermatological practice

Aspects of bacterial resistance to the major classes of antimicrobials used in veterinary dermatology are presented in this review. Resistance of gram-positive and gram-negative bacteria to tetracyclines, macrolide-lincosamide-streptogramin antibiotics, chloramphenicol, mupirocin, sulphonamides, trimethoprim, aminoglycosides, fluoroquinolones and β-lactam antibiotics are depicted with respect to the different mechanisms of acquired and intrinsic resistance. Examples are given for the three major resistance mechanisms, enzymatic inactivation, decreased intracellular drug accumulation and target modification. In addition, basic information about mobile genetic elements which carry resistance genes, such as plasmids, transposons and gene cassettes, and their modes of spreading via transduction, conjugation, mobilization and transformation is provided.     

Risk factors for fecal shedding of Salmonella from horses in a veterinary teaching hospital

Identification of risk factors for horses shedding Salmonella in their feces helps identify patients at-risk of infection and protect the overall population through heightened biosecurity. Fecal samples from 230 hospitalized horses were cultured for Salmonella spp. Historical data were collected on 21 putative risk factors and assessed for association with the risk of a horse being culture positive using forwards stepwise logistic regression. Salmonella was isolated from 13 horses—most commonly from either the first (n=5) or second (n=4) sample collected. Only presenting complaint (confounded by age, breed and gender) was significantly (P≤0.05) associated with positive Salmonella-culture results. Analysis of residuals showed that the model was robust, but individual risk-factor estimates were changed by removal of outliers. Overall, presenting complaint (for example, lower-respiratory-tract disease) was the most important indicator of culture status.     

Association between serum cytotoxicity and selected clinical variables in 240 horses admitted to a veterinary hospital.

A total of 378 serum samples from 240 hospitalized horses and 47 sera from healthy control horses were assayed for growth effects on actinomycin D-treated L929 cells. On average, patient and control sera stimulated cell growth; however, mean percentage of the relative growth index (RGI) of sera from clinical cases was significantly (P less than 0.001) lower than that of control sera. Approximately 35% of patient sera and 6% of control sera had tumor necrosis factor-like cytotoxic activity for L929 cells (ie, RGI less than 100%). Sera from horses with either peritoneal leakage of gastrointestinal tract contents or any bacterial infection were significantly (P less than 0.05) more cytotoxic than sera from horses that did not have these clinical factors. A clear tendency was evident for horses that had the highest serum cytotoxicity (RGI less than 75%) to also have clinical profiles suggestive of endotoxemia. Fever, leukopenia, diarrhea, and gastrointestinal tract leakage were significantly (P less than 0.05) overrepresented among these horses, compared with horses without serum cytotoxicity. Bacterial infections and abdominal surgeries were also increased in this group, but not significantly. Of the 14 horses with serum RGI less than 75%, 13 had some form of gastrointestinal tract disease and the other had gram-negative septicemia. Survival to discharge was significantly (P less than 0.05) lower among horses in the high-cytotoxicity group than among horses without serum cytotoxicity. Diarrhea and bacterial infections were the only clinical factors found more frequently in horses with low serum cytotoxicity than in horses without serum cytotoxicity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Neuromuscular blocking effects of certain antibacterial agents in pigs and lambs

The neuromuscular blocking effects of several antibacterial agents were examined in young pigs and lambs using a sciatic nerve-gastrocnemius muscle preparation. Intravenous administration of streptomycin, neomycin or tetracycline produced a decrease in indirectly stimulated contractions of the gastrocnemius muscle; whereas, chloramphenicol, sulphadiazine and penicillin-G had no discernible neuromuscular blocking effects. Present findings confirm the neuromuscular blocking activity of certain antibiotic agents, and indicate the potential for this adverse side effect in food-producing animal species.     

Aerobic bacterial isolates in horses in a university hospital, 1986-1988

Bacterial isolations were reviewed from equine trachea, guttural pouch, uterus, wounds, abscesses, blood, synovial fluid, and abdominal fluid submitted to the Clinical Bacteriology Laboratory of the School of Veterinary Medicine at the University of Montreal for aerobic bacterial culture from 1986 to 1988. Of the 733 samples submitted, 324 (44%) were positive for bacterial growth, and 233 antimicrobial sensitivity tests were performed. Seventy-six percent of all positive samples yielded one bacterial species and two were isolated from 22% of positive samples. Streptococcus zooepidemicus, Escherichia coli, and Actinobacillus spp. were isolated from 39%, 18%, and 15% of the samples, respectively.

Bacterial growth was most common from guttural pouches, wounds and abscesses, and transtracheal washes (TTW), but was less common from uterus, blood, abdominal fluid, and synovial fluids. Streptococcus zooepidemicus was the most common bacterium recovered from guttural pouches, TTW, uterus, and wounds and abscesses. Escherichia coli predominated in abdominal fluids, blood, and synovia. Bacterial sensitivities to common antimicrobials are presented.

     

The usability of peritoneal lactate concentration as a prognostic marker in horses with severe colic admitted to a veterinary teaching hospital

Colic can be a life‐threatening condition in horses and there is a need for parameters that can help determine the prognosis and need for surgery. The aim of the study was to investigate whether peritoneal fluid (PF) lactate concentration is useful for this purpose in horses with severe colic presented to a veterinary hospital. During a 16 month period, the peritoneal fluid (PF) lactate concentration was measured in 74 of 760 colic horses admitted to the Utrecht University equine clinic using a portable analyser. When comparing survivors and nonsurvivors, heart rate, PF and blood lactate concentrations and blood glucose concentration were significantly higher in horses that did not survive. No horse with a PF lactate concentration >9.4 mmol/l survived. The presence of a strangulating lesion was also significantly associated with nonsurvival, as was PF colour: no horse with red PF survived in the present series. In horses with yellow PF, the blood glucose concentration was correlated with the presence of a strangulating intestinal lesion. Peritoneal lactate concentrations can be easily and rapidly measured using a portable analyser and may be useful in assessing the prognosis and/or need for surgery in equine colic cases.     

Retrospective study of perioperative antimicrobial use practices in horses undergoing elective arthroscopic surgery at a veterinary teaching hospital

Perioperative antimicrobial administration practices were evaluated retrospectively in 97 horses undergoing elective arthroscopy, and antimicrobial use was compared with standard recommendations for perioperative prophylaxis. Parenteral antimicrobials were administered perioperatively to 95/97 (98%) horses, 88 of which received intravenous sodium penicillin. Time from 1st dose until 1st incision ranged from 30 to 390 min [142 ± 55.6 min, mean ± standard deviation (s), median 135 min], and the first incision was performed greater than 2 half-lives after administration of sodium penicillin in 86/95 (91%) cases. Overall duration of therapy was 30.8 ± 24.2 h (mean ± s). Six (6.3%) horses received only a single preoperative dose, while 63 (66%) horses were treated for 24 h or less. While objective data regarding optimal perioperative antimicrobial prophylaxis are limited, the antimicrobial use practices observed here commonly deviated from standard recommendations for perioperative prophylaxis.     

Nosocomial infections and bacterial antibiotic resistance in a university equine hospital

A base-line study of bacteria isolated from horses admitted to the Veterinary Medical Teaching Hospital during a 6-month period was performed to determine the extent of multiresistant nosocomial infections caused by gram-negative aerobic bacteria other than Salmonella spp. Results of this study indicated that 21.9% of the 105 horses from which cultures and sensitivities were available had developed nosocomial gram-negative aerobic infections, with high rates of resistance to gentamicin, kanamycin, and trimethoprim sulfadiazine, three of the most often prescribed antibiotics in this hospital. In addition, a prospective study of antibiotic-resistant bacteria of fecal origin was performed to determine whether there was a change in the degree of antibiotic resistance of a horse's intestinal flora while the horse was hospitalized. Bacterial culturing for gram-negative lactose fermenting bacteria was done on fecal specimens collected directly from the rectum on day 1 and day 7 of a horse's hospitalization. Susceptibility testing was done on each isolant. Of the 24 paired fecal specimens obtained, Escherichia coli and Klebsiella sp isolated on day 7 were resistant to a significantly higher number of antibiotics than day 1 isolants (P = 0.003, P = 0.043, respectively).     

Guidelines for planning studies to determine the resistance of infectious agents of veterinary relevance

This paper describes the most important criteria for the planning of statistically sound and representative studies on the prevalence of antimicrobial resistance among pathogenic bacteria from animals. The statistical design of the study is of particular importance and therefore described in some detail. The existing published data about antimicrobial resistance are mostly retrospective summaries of results and do not give a true picture of the resistance situation. The authors propose to conduct a pilot study initially because many basic elements for a sound study design are still not known. The systematic recording and assessment of the target variables including the necessary quality assurance are an important prerequisite. Moreover, potential cause variables can be further narrowed down and conclusively identified. To ensure the representativity of the cross-sectional study and avoid potential bias, it is important to achieve the highest possible response rate. This will form the basis of a scientifically sound resistance monitoring programme which should be the joint responsibility of regulatory authorities, industry and academia.     

The resistance of antimicrobial agents in Salmonella from veterinary sources in Australia from 1975 to 1982

SUMMARY A survey of antibiotic resistance in 1,287 strains of Salmonella from bovine, porcine and avian sources in Australia was carried out from 1975 to 1982. Isolates were tested against ampicillin, chloramphenicol, furazolidone, neomycin, streptomycin and tetracycline. Resistance was found to streptomycin in 286 isolates and to tetracycline in 282 isolates. Resistance to other antimicrobials was low and was unrelated to source. One hundred and seventy-three isolates showed multiple resistance to 2 or more antimicrobial agents with resistance to streptomycin and tetracycline being the most common. The overall level of resistance did not change over the period examined.     

The economics of a veterinary hospital

The costs involved in building a small animal hospital are discussed. Running costs and gross turnover are compared immediately before and after building.

SUMMARY

We have attempted to discuss in the frankest possible manner the economics of a purpose-built small animal hospital. It must be remembered, however, that the financial return is only one factor to be considered in such a project. Pleasant working conditions for veterinary surgeon and lay staff, improved waiting facilities, more efficient reception, better surgical facilities and better patient accommodation have led in this practice to a much improved standard of veterinary medicine and surgery. Thus animal, client, staff and veterinary surgeon all benefit from improved facilities.
During the next decade there is little doubt many more hospitals will be built in this country. At the moment many of our colleagues are considering taking what is probably the biggest, single, financial investment of their lives. We hope this paper will assist them in making this decision.
Résumé. Les auteurs donnent des précisions sur les dépenses à engager pour la construction d'un hôpital pour petits animaux et sur les frais généraux et le chiffre d'affaires brut immé-diatement avant et après la construction.
Zusammenfassung. Die bei der Errichtung einer kleinen Tierklinik entstehenden Kosten werden besprochen. Laufende Kosten und Bruttoumsatz unmittelbar vor und nach dem Bau werden miteinander verglichen.